An Adaptive DC-Link Voltage Control of a Multifunctional SPV Grid-Connected VSI for Switching Loss Reduction

Abstract

In the proposed method in this article, to minimize the burden on the switches of the multifunctional grid-connected voltage-source inverter (MFGCVSI), the voltages of dc-link split capacitors are adjusted according to power injection from the MFGCVSI. The MFGCVSI is used to control the active power injection from solar photovoltaic (SPV) power generation to the main grid and loads, load reactive power compensation, harmonic mitigation, and main grid current total harmonic distortion within 5 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\%$</tex-math></inline-formula> . In such a case, the voltages of split capacitors depend on the rated power injection from the MFGCVSI. The power generated from the SPV system and the loads that are connected at the point of common coupling vary with respect to time. It is observed that the selection of rated dc-link voltages during low power injection from the MFGCVSI leads to additional switching stress and higher switching losses. Therefore, to reduce the burden on inverter switches and switching losses, the reference dc voltage is reduced under low power injection from the MFGCVSI. A model predictive controller with a multiconstraint technique is used in the proposed method for balancing the dc-link capacitor voltages and average switching frequency reduction. The proposed method is validated through simulation and hardware setup.